Preheat the oven to 350°F. Cook the pasta to al dente per the directions on the back of the Mueller’s® spaghetti pasta box. Drain and set aside. Spray a 9x13 baking dish with cooking spray, set aside.
In a large skillet over medium-low heat add the butter and let it melt. Add the onions and cook until translucent, stirring occasionally, 5-8 minutes. Add the sliced mushrooms and cook until softened, stirring occasionally, 5 minutes. Add the garlic and Italian seasoning, mix it in until fragrant, 30 seconds.
Add the cream cheese to the pan and stir constantly, breaking it up until melted. Add the cream of mushroom soup, sour cream, and milk, stir to combine.
In a very large bowl or the stockpot you cooked the noodles in, add the cooked spaghetti, the sauce from the skillet, the diced turkey, and frozen peas. Mix it all together until combined. Add this to the prepared baking dish and smooth it out.
Top with shredded mozzarella. Cover with nonstick foil and bake for 45 minutes, until bubbly. Take the foil off and top with the crushed butter crackers. Place it back in the oven for 10-15 minutes until golden brown on top. Add a garnish of fresh parsley if desired, serve immediately.